It builds on top of Invoke (subprocess command
execution and command-line features) and Paramiko (SSH
protocol implementation), extending their APIs to complement one another and
provide additional functionality.

Multiple tasks may be given in a single CLI session, e.g. fab build
deploy;

Much more - all other Invoke functionality is supported - see its
documentation for details.

I’m a user of Fabric 1, how do I upgrade?

We’ve packaged modern Fabric in a manner that allows installation alongside
Fabric 1, so you can upgrade at whatever pace your use case requires. There are
multiple possible approaches – see our detailed upgrade documentation
<http://fabfile.org/en/latest/upgrading.html> for details.